With the development of digital multimedia technology, content providers provides increasingly rich multimedia contents, such as digital music, video and movies. Moreover, the requirement of content providers on security protection of digital multimedia content is getting higher. DRM security technology is a very popular and important digital content security protection means in the recent years, and its application in music, movies and other digital multimedia fields is being widened.
During application of the DRM, sometimes it is required to encrypt and save the content of a multimedia file, and decrypt the content of the multimedia file before a user uses it. However, with the enrichment and increasing of the music, movie and other digital media content to be downloaded, the encryption and decryption processing on the whole content of a file during downloading and consumption will lower processing efficiency and affect user experience, therefore it is necessary to provide an improved technical solution to solve this problem.